ABSTRACT: OBJECTIVE: To Study The Short-term Effects Of Slow Repetitive Transcranial Magnetic Stimulation (rTMS) Of The Motor Cortex On Cortical Excitability And Handwriting In Patients With Writer's Cramp. BACKGROUND: Cortical Excitability Of The Primary Motor Cortex Is Abnormally Enhanced In Patients With Writer's Cramp. Therefore, Reducing Cortical Excitability By Low-frequency RTMS Of The Motor Cortex Might Result In Beneficial Effects On Handwriting In Writer's Cramp. DESIGN/METHODS: We Studied The Effects Of Subthreshold 1-Hz RTMS On Motor Threshold And Cortico-cortical Excitability Using The Paired-pulse Technique In Seven Patients And Seven Controls. In Another 16 Patients And 11 Age-matched Controls We Evaluated Changes In Cortical Excitability By Measuring The Stimulus-response Curve And The Postexcitatory Silent Period Before And After Subthreshold 1-Hz RTMS. In Addition, We Analyzed The Handwriting Before And 20 Minutes After 1-Hz RTMS. RESULTS: In The First Experiment, Low-frequency RTMS Resulted In A Normalization Of The Deficient Cortico-cortical Inhibition In The Patients Without Affecting Motor Threshold. In The Second Experiment, 1-Hz RTMS Resulted In A Significant Prolongation Of The Postexcitatory Silent Period Without Affecting The Stimulus-response Curve In The Patient Group. Moreover, The Dystonic Patients Showed A Significant Reduction Of Mean Writing Pressure After Subthreshold 1-Hz RTMS That Was Associated With Clear But Transient Improvement In Six Patients. CONCLUSIONS: In Some Patients 1-Hz RTMS Can Reinforce Deficient Intracortical Inhibition And May Improve Handwriting Temporarily. Our Data Support The Notion That Reduced Intracortical Inhibition Plays A Part In The Pathophysiology Of Focal Dystonia. MAIN MESH HEADINGS: *Handwriting *Magnetics Motor Cortex/*physiopathology Muscle Cramp/*physiopathology ADDITIONAL MESH HEADINGS: Adult Analysis Of Variance Evoked Potentials, Motor/physiology Human Middle Age Support, Non-U.S. Gov't 1999/02 1999/20 03:12 PUBLICATION TYPES: JOURNAL ARTICLE LANGUAGES: Eng